1. Field of the Invention (Technical Field)
The present invention relates to oil and gas wells, and more particularly to a system for providing a controlled flowback from the wellbore after a treatment procedure.
2. Background Art
Most oil and gas wells require some form of stimulation to enhance hydrocarbon flow to make or keep them economically viable. The servicing of oil and gas wells to stimulate production requires the pumping of fluids under high-pressure. The fluids are generally corrosive and abrasive because they are frequently laden with corrosive acids and abrasive propellants such as sharp sand, shale, coal or the like.
The components which make up the wellhead, typically, valves, a tubing hanger, a casing hanger, a casing head, and a blowout preventer (BOP) system, are generally selected for the characteristics of the well and not the flowback process and procedures. The abrasive propellants and or corrosive fluids required for well fracturing and stimulation procedures are required to fracture the formation to allow oil or gas to flow into the wellbore. After the well fracturing process has been completed, a procedure called flowback is conducted. This procedure is a controlled process of allowing fluids to flow from the wellbore following treatment either in preparation for a subsequent phase of treatment or preparation for cleanup and returning the well to production.
The clean up period or flowback, generally follows a stimulation (called a frac job) treatment during which time treatment fluids return from the reservoir formation and wellbore. Depending on the treatment, the cleanup period can be short and uncomplicated. However, in more complicated and complex larger fracturing jobs the flowback process can become much more complex and hazardous. The controlled flowback process should be conducted carefully to avoid jeopardizing safety, equipment, environment or the long-term efficiency of the well stimulation.
There are many different methods, techniques, processes and types of flowback practiced in the oil and gas industry used to cleanup a wellbore and formation after the fracturing process has been completed. The prior art flowback procedures all generally utilized the same or similar types of components, parts, apparatuses, and methods, that are standards and known by those experienced in the art in the oil and gas industry. Most known flowback methods use some sort of part, apparatus or technique of controlling the pressures and rate of velocity of the fluids and propellants returning from the formation during clean out.
These parts are commonly know as wellhead Christmas trees, casing valves, frac valves, flowback trees, frac stacks, casing isolation tools, tubing isolation tools, frac Y's, blowout preventer (BOP), chokes, choke manifolds, adjustable chokes, positive chokes, ceramic chokes, inline chokes, choke inserts, choke beans, choke nipples, cage nipples, and many various other apparatuses that attach, screw on, bolt on, hammer on, and clamp on to the flowback lines, equipment and parts. These parts and apparatuses or combination thereof, are used to perform a flowback and cleanup of wellbore and well formations.
There are many problems associated with the conventional methods and practices used to flowback a well using current industry standards, equipment or methods. One such problem is the installation of flowlines that connect or mate from a horizontal position to a targeted tee then to a vertical targeted tee, then back to line laying in the horizontal position on the ground. The problem occurs because the distance and heights vary from location to location for various reasons, terrain, equipment configuration, styles, and placement of the wellhead and the surface casing. For these reasons, flowline connections to flowback tree or horizontal valves, used to connect, vary and require pipe to be cut, welded or fabricated to mate connections. Because of weather elements such as rain, wind, mud, snow, and cold, this function cannot be performed in an optimum environment so the quality and safety of the work performed could be compromised. Pipe threading and welding or fabricating are best preformed in a controlled environment. Other common problems that occur during installation are that many variables exist, such as lines that attach to choke manifolds or flowback tanks and earthed pits, all require variable lengths to mate connections. There are other problems, such as current flowbacks do not have a way to contain the pressures or corrosive acids and abrasive propellants such as sharp sand. The problem arises because the propellant fluids, acids, chemicals, and fracture products pumped into the wellbore formation during (flowback) clean up, travel at high velocity causing washing out of the lines and equipment from the inside out. The current flowback practices have no method or system to contain, control or monitor a washout. In addition, there is not a system that detects a washout or a warning system to notify when a potential washout might occur. When this event occurs, gases, propellants, fluids, acids, and chemicals could vent to the atmosphere causing unsafe conditions, injury and environmental contamination.